One of the most characteristic features of skeletal muscle is its remarkable ability to adapt to different stimuli. Throughout life the skeletal muscle is permanently adapting to internal (ageing/sarcopenia resulting in muscle loss) or external changes (physical activity results in muscle hypertrophy; while injury results in muscle recovery; and bed rest results in muscle atrophy). These influences modify structural, biochemical and molecular variables of the different skeletal muscle fibers. For the adaptation of myofibers the activation and myogenic differentiation of satellite cells, the so-called stem cells of the skeletal muscle, are required. After exercise training, for example, satellite cells fuse together with the enlarging or repairing myofibers.
Niacin, also known as vitamin B3 or nicotinic acid, is a water-soluble vitamin that prevents the deficiency disease pellagra. It is an organic compound with the molecular formula C6H5NO2 as defined by the formula (I).

It is a derivative of pyridine, with a carboxyl group (COOH) at the 3-position. Other forms of vitamin B3 include the corresponding amide, nicotinamide (“niacinamide”), where the carboxyl group has been replaced by a carboxamide group (CONH2), as well as more complex amides and a variety of esters. The terms niacin, nicotinamide, and vitamin B3 are used interchangeably to refer to any one of this family of molecules, since they have a common biochemical activity.
Trigonelline is an alkaloid with chemical formula C7H7NO2 as defined by formula (II)

Trigonelline is a niacin (vitamin B3) metabolite which is excreted in the urine. It is formed by the addition of a methyl group to the nitrogen atom of niacin. Trigonelline is also found in coffee, where it may help to prevent dental caries by preventing the bacteria Streptococcus mutans from adhering to teeth.
US 2005/0226948 (Lee et al) discloses a Fenugreek seed extract containing 4-hydroxyisoleucine and a number of other compounds, including niacin and trigonelline. These combinations are used to enhance glucose transport into muscle cells.
US2007/0105793 (Hendrix) discloses a composition useful for treatment of hyperlipidemia, hypercholesterolemia and hyperglyceridemia that contains niacin and derivatives.
US2007/0259861 (Krantz) discloses compositions containing a non-steroidal antinflammatory drug (NSAID) in combination with a prostaglandin mimetic (which can include various niacin derivatives. These combinations are used for pain and/or inflammation relief.